1. Field of the Invention
The present invention relates to a cut length adjusting apparatus capable of cutting a continuous paper web into equal lengths and laterally into various cut lengths, and especially to such an apparatus applicable to a folding machine in a rotary press (in particular, a rotary press for newspapers).
2. Description of the Prior Art
The requirement for effecting unequal length cutting with a cutting drum include the capability of effecting an adjustment of cut-off lengths of superposed sheets (as will be described later) depending upon a total number of pages after having switched from straight folding to collective folding (See FIG. 3(a)), the capability of effecting an adjustment when it is desired to increase a circumferential length of a pattern, and the like.
To that end, as shown in FIG. 3, in the prior art either one or both of a pair of cutting cases 02 each holding a knife blade 01 are moved within a groove 04 of a cutting drum 03. And, after a cut length between the knife blades 01 and 01' is adjusted by means of a spacer 05, the cutter cases 02 are fixed by means of wedges 06.
However, the apparatus in the prior art as described above gives rise to the following problems:
(1) While it is necessary to change a cut-off length between a folded sheet held in contact with a cutting drum (hereinafter called "sheet A") and a folded sheet superposed on the first folded sheet (hereinafter called "sheet B") depending upon the superposed number of the sheets A and B when straight folding has been switched to collective folding, according to the method in the prior art it a great amount of time for extracting the wedges, and a total adjustment time of about 10 minutes, is necessitated. PA1 (2) Since the cut-off lengths of the sheets A and B are adjusted by means of the spacers, human labor is necessarily required to exchange such. Hence, a remote control or unmanned operation cannot be realized. PA1 (3) The adjustment of the cut-length size of the sheets in a stepless manner cannot be achieved. PA1 (1) A cutting drum is formed of an outer cylinder supporting one knife blade and an inner cylinder disposed within the outer cylinder and supporting the other knife blade. A helical gear mounted on the outer cylinder so as to be slidable in the axial direction is moved by means of a moving device, and the outer cylinder is made to rotate in the circumferential direction by the action of a driving helical gear meshed with the first-mentioned helical gear and fixed to the folding drum. PA1 (2) During the period when the outer cylinder rotates in the circumferential direction, rotation of the inner cylinder is restrained by the provision of a gear, such as a helical gear or the like, mounted to the shaft of the inner cylinder and which gear is always in meshing engagement with another driving gear such as a driving helical gear or the like fixed to the folding drum. PA1 (3) A reversal of the operative relationship described in paragraphs (1) and (2) above is acceptable. That is, rotation of the inner cylinder and a restraint of the rotation of the outer cylinder are acceptable. PA1 (4) The helical gear that is slidable in the axial direction as described in paragraph (1) above, could be the helical gear mounted to the folding drum.